Diamondbacks right-hander Riley Smith walked off the mound one night last month. He had just completed his first inning of work in the major leagues. He had also just served up a grand slam to the Colorado Rockies’ Charlie Blackmon.

“Giving up a grand slam in my debut,” Smith recalled. “That can be overwhelming.”

For Smith, it turned out not to be. He retired the side in order the following inning, and he has proceeded to roll through his next four appearances, including another lengthy one in Tuesday night’s 7-0 win over the Texas Rangers.

Smith’s five shutout innings in relief of another Smith — Caleb Smith, a left-hander — helped the Diamondbacks to what might have been their tidiest victory of the season. David Peralta had three hits. Carson Kelly connected for a three-run homer. Caleb Smith wiggled out of an inauspicious start to toss four scoreless innings before handing off to his fellow surnamed hurler.

“You talk about the type of game we’re expecting to play,” manager Torey Lovullo said, “I think that was it.”

For Riley Smith, the outing was a continuation of what has been a revelatory rookie season, the kind of strong showing that could earn him a leg up on a roster spot heading into next year.

“If you pitch good, then it puts you in a better spot,” Smith said. “If you pitch bad, it doesn’t.”

In 16 1/3 innings in the big leagues, he has allowed just three earned runs. Not every outing has been smooth — his debut against the Rockies on Aug. 26 wasn’t, nor was a five-walk relief appearance against the Los Angeles Dodgers two weeks ago — but each time Smith has managed to keep things from getting out of hand.

To say Smith has come out of nowhere isn’t entirely accurate. He has been working his way through the Diamondbacks’ system since the club drafted him in the 24th round out of Louisiana State in 2016. His prospect status rose last year when he had a dominant three-month stretch in the Southern League in Double-A.

But while he was added to the club’s 40-man roster last offseason as a check against the Rule 5 draft, it has taken a fair amount of attrition for him to work his way up to the majors this year.

He has capitalized on the opportunity. Even after the rough debut. He entered the game that night against the Rockies with two on and none out. Three batters later, he left a 2-0 fastball over the middle of the plate and Blackmon destroyed it.

“I got it out of the way,” Smith said, smiling. “It’s going to come at some point. The thing about that is, if you look at the line, I gave up a grand slam. But if you look at the pitches, I made one bad pitch that outing — in my head. Other people may see it differently, but I felt really good about the outing.”

There was no disputing the quality of his performance on Tuesday night. After Caleb Smith settled down and got through four innings — he walked the first three batters of the game only to somehow escape the first inning unscathed — Riley Smith took over a 2-0 game and appeared to hardly break a sweat.

He worked quickly. He threw strikes. He got outs. Granted, he was facing a Rangers lineup that ranks as the most inept in the American League, but he still managed to allow only five hits — all singles — while issuing no walks in five breezy innings.

He said his outing against the Dodgers on Sept. 10 was still on his mind as he worked on Tuesday night.

“When I pitched against the Dodgers, I walked five and that really made me mad,” he said. “So my focus in the last couple of weeks has been to fill up the strike zone in all my bullpens leading to an outing, and we have personal goals as a pitching staff and as a bullpen to get ahead and win the first three (pitches of an at-bat). That was my main focus. That’s what I was trying to achieve.”

Where Smith ends up next year remains to be seen. He came through the minors as a starter and could get a chance in that role. Or the club could like him enough out of the bullpen that it won’t try to fix what isn’t broken. Either way, the way he has pitched has helped him make a name for himself — especially on a night when two other Smiths also played. (Pavin Smith started at first base.)

“I think anything I can do to help the team obviously makes me more valuable as a player and as a pitcher,” Riley Smith said. “I just consistently try to get out there and throw strikes, fill up the zone, get outs quick and let them hit it. That benefits me in the long run. If I throw good, that benefits me. You’ve got to throw good to stay.”